The present invention relates to a fixing apparatus for fixing the neck of a subject.
In recent MRI (Magnetic Resonance Imaging) apparatuses, the diameter of the bore is made larger to allow physicians to diagnose a subject in various positions.
When the imaging of the subject's neck bone is required under the condition that the subject's neck is bent at various angles, a neck fixing apparatus shown in FIG. 1 is used.
Referring to FIG. 1 (a), there is shown a perspective view of the prior-art neck fixing apparatus, wherein a base portion 2 disposed on a surface on which the subject is mounted is provided with a head support 4 for mounting the subject's head, and the head support 4 is attached using threads 6.
In the above-constructed neck fixing apparatus, the head support 4 is rotated with respect to the base portion 2 by loosening the threads 6, and maintained at a selected position by driving the threads 6.
FIG. 1 (b) is a view taken in the direction indicated by arrow A in FIG. 1 (a), wherein the neck fixing apparatus is put on the subject. As shown in FIG. 1 (b), the head support 4 is provided with a cushioning material (pad) 8, and the subject's head 10 is mounted on the cushioning material 8 and fixed to the head support 4 using a band 12 fitting on the forehead.
Although the neck is similar to other joints such as the elbow, knee, wrist or ankle in that they are movable, it is different from the other joints in some ways. That is, the joint at the elbow, knee, wrist, ankle or the like is moved with its center of rotation fixed, whereas the neck consisting of seven cervical vertebrae is moved with its center of rotation varied because the individual vertebrae are moved separately.
When the subject's neck is bent at various angles using the neck fixing apparatus constructed as shown in FIG. 1, the motion of the subject's neck bone which has varying centers of rotation does not match with the motion of the head support 4 which has a fixed center of rotation.
Therefore, discordance occurs between the subject's head 10 and the head support 4, resulting in problems that the band 12 gets off from the subject's head 10 and/or touches the subject's eyes or nose.